Originally Posted by resopaton

5W30 is typically recommended for drivers who live in colder climates. I believe the magic number is 20 degrees F. So, living in climates that drop below 20 degrees F 5W30 is recommended, in most cases.

Aside from climate, todays engines were built with tighter bearing clearances for better fuel economy, thus using a 5 weight (5W30) is recommended.

Older engines engineered with larger bearing clearances, or vehicles with high miles more than likely will achieve ideal oil pressures running with a 10 weight oil (10W30).

Hope this helps...